Alkylation of aromatic hydrocarbons



"Patented 21, 194

ALKYLATION 0F snoMA'rrcnYnnocannons can B. Linn, Chicago, Ill.,"assignor to Universal Oil Products Company, Chicago, Ill., a corporation oi Delaware No Drawing.

Application February 11, 1942, Serial No. 430,508

11 Claims. (Cl.- 260-671) hydrocarbons. It is'more specifically concerned with a simple and easily regulated process involving the use of a liquid catalyst which is altered only slightly in the course of the reaction but which catalyzes the desired reactions with a maximum of efllciency.

Processes for the formation or more-highly alkylated aromatic hydrocarbons from-less-high- 'ly alkylated a'romatiohydrocarbons are of importance not only from the the standpoint of producing high antiknock -motor. fuel .iractio'ns bons as ethyl benzene which are useful as'inter mediates in the production of synthetic organic chemicals such as styfilnf In one speciflc em e prises producing alkyl fluorides by reacting'an excessof hydrogen fluoride with oleflns present in a hydrocartion containing both oleflns and normal pa ii removing the resultant alkyl j fluorides and excess hydrogen fluoride as a solution from imconverted normal p'araflins which separate as an upper layer from the heaviermlxture. of alkyl fluorides and hydrogen fluoride, commingling said solution comprising alkyl fluorides and hydrogen fluoride with an aromatic hydrocarbon-underfialkylating conditions to form,

a reaction mixture containing substantial proportions of aikylated aromatic hydrocarbons, separating unconverted aromatic hydrocarbons, ,alkylated' aromatic hydrocarbons, and used hydrogen fluoride from said reaction mixturerecycling unconverted aromatic hydrocarbons to further reaction with alkyl fluorides, and reiairning at least a portion *ot said .used hydrogen fluoride to further contact with the charged fraction containing both oleflns and normal par-.

amns; 7.

According to the process the present invention, hydrogen fluoride is utilizable for reacting with oleflns to produce allryl fluorides which are readily separable trons unconverted normal parand also as catalyst in the alkylation of aromatic as benzene, toluenc, al-' kylated benzenes, and poly-cyclic aromatic hydrocarbons. Hydrogen fluoride, when substantially anhydrous, is a liquid boiling at about 20 nt the present'invention comprises a process for the manufacture of alkylated aromatic hydrocarbons which combut for preparing alkylated aromatic hydrocar-v I C. and accordingly it can be used in apparatus which is cooled to maintain temperatures below this point or it can be used at a higher temperature ii .sufllcient pressure is maintained upon the system. Theplefln-containing fraction used in the flrst step 'of the process may consist of cracked gases containing little or no isoparafflns since isoparafllns present would undergo alkylation in the flrst reaction zone in which it isdesired to produce alkyl fluorides. The olefin-containing charging stock may comprise. substantially pure oleflns asethylene, propylene," butylene, amylenes, etc., or these may be diluted with normally gaseous straight chain 'paraflins. In this stage of the process the olefin-containing fraction is contacted with an excess or liquid hydrogen fluoride at. agtern'perature bet en about 50 and about +50 0. but preferag; at a temperature between emot -50 and 0 C.

although a. temperature as high as room temv molecular proportion of hydrogen fluoride is emperature is frequently employed. The contacting. operation may be carried out by anyof the usual methods employed for suchpurposes. In order to convert substantially all of the oleflns into alkyl fluorides, more than an equivalent ployed. This excessof hydrogen fluoride m ay, with advantage, be as high as 200 molecular proportions per 1 molecular proportion of oleflns charged. Ihave also found that the excess of hydrogen fluoride over oleflns assists in separating the resultant alkyl fluorides from the uncon- 'verted parafllnic hydrocarbons/because o e relatively high solubility of alkyl fluorides 6612 0 1- .uid hydrogen fluoride of to concentration. At temperatures higher than those prev ferred for-the addition or hydrogen to oleflns,-

polymerization occurs which interferes with the direct conversion of theoriginal oleflns into alkyl fluorides.

After the hydrofluorinatlon step, the product together with unconverted paraiflns is sent' toa settling chamber (assuming always apressure on the system in excess of the combined vapor pressures oi the components) in which the top layer 9 consists essentially ofnormal paraflins such as propane, butane, etc., which can be disposed oi as desired, whilethe bottom layer comprises a solution of allryl fluoridw as ethyl fluoride, isopropyi fluoride, butyl fluorides, etc., in hydrogen fluoride. v

. The alkyi fluoride-hydrogen fluoride" layer so separated from is then directed to a ree actor where it is contacted with a liquid hydrocarborr charge consisting entirely or partially oi carbons.

. amounts of poly-ethyl benzenes.

aromatic hydrocarbons such as benzene or its homologs. When the process is utilized for the production of alkylated aromatic hydrocarbons of gasoline boiling range, it will be apparent that relatively high boiling aromatics should not be "alkylated, otherwise a productwill be obtained boiling higher than the boiling range of gasoline.

During the alkylation step hydrogen fluoride is liberated by the interaction of an aromatic as benzene with an alkyl fluoride such as ethyl fluoride.

. The alkylating step of the process is preferably 1 carried out ata temperatureof froni about to to about 150 C. but preferably at a temperature 'of from about 10 to about 30 C. By carrying out the alkylation reaction so that an excess of benzene is present, generally up to approximately times the molecular proportion of the alkyl" fluoride," formation of :poly-alkylated' aromatic hydrocarbons is kept relatively low. The result ant product is fractlonally distilled to separate therefrom the excess aromatic hydrocarbon which is recycled to the process while the alkylated aromatic hydrocarbons are fractionated into monoalkyl and poly-alkyl aromatic hydro- The process of the present invention is utilizable for converting benzene and an ethane ethylene fraction, such as that obtained by pyrolysis of hydrocarbons, into relatively high yields of mono-ethyl benzene together with small In the first stage of theprocess liquid hydr gen fluoride of for example 98-100% concentra on iscontacted with the ethane-ethylene ,f'raction at a'tempera- 'ture between about -5o* and about -2o' 0. and substantially all of the ethylene is converted into ethyl fluoride which is soluble in the excess hydrogen fluoride present. Suflicient pressure is maintained upon the resultant mixture to keep the hydrocarbons and hydrogen fluoride in liquid state. The unconverted ethane is then substantially separated as an upper layer from a lower layer comprising essentially ethyl fluoride and hydrogen fluoride. The lower layer containing both' ethyl fluoride and hydrogen fluoride is then contacted with benzene at a temperature between about 0- and 150 C; in the presence of an additional quantity of hydrogen fluorida- If desired, the mixture of hydrogen fluoride and ethyl fluoride may be introduced at intermediate points between the entrance and the exit of the alkylating zone which also contains the aromatic hydrocarbon, benzene. It is also preferable that at least a portion of the allrylation reaction mixture be withdrawn from near the exit of the alkylation reactor and be recycled to commingle with the alkyl fluorides, benzene, and hydrogen fluoride charged thereto. The products from'the alkylation reactor are then separated into a hydrogen fluoride layer and a hydrocarbon layer, the latter comprising essentially benzene and ethylated benzenes. The hydrogen fluoride layer so sepa ated from the-hydrocarbon'products of the alkylation reaction is recycled to further use in either or both stages of the process' as described. Fractionation of the hydrocarbon layer' of the' 'alkylation product separates unconverted benzene from mono-ethyl benzene and more- -highly ethylated benzenes.

The exact temperature and pressure to be em ployed inconverting oleflns into alkyl fluorides and inalkylating different aromatic hydrocarbonswith various alkyl fluorides will depend upon the activity and physical characteristics-of the asrasos reactants involved as well as the proportion and much less soluble 'in liquid hydrogen fluoride and is therefore readily separable as an upper layer from the hydrogen fluoride solution of ethyl fluoride under the operating pressure which is sufthe ethane, ethyl fluoride, and hydrogen fluoride. The solution of ethyl fluorldein hydrogen fluoried can then be reacted with benzene to produce' ethyl benzene while the ethane is discharged from the process. The alkylation stage is accordingly carried out under'substantially liquid phase conditions without interference of ethane which sometimes occurs when an ethane ethylene fraction is introduced directly to an alkylation reactor in which benzene is contacted with liquid hydrogen fluoride. The present combination process is therefore useful in forming the/ethyl fluoride, separating'it from the unconverted ethane and eflecting'the alkylation of benzene under conditions which gives high yield of monoethyl benzene and relatively small amounts of -more-highly ethylated benzenes. The following examples are introduced as rep described, although withno intention of unduly limiting the generally. broad scopeof the invenz'zample.. l f In a process substantially astiescflbed, .3 molecular proportions of a propane-propylene fraction containing about 30% of the latter are con.- tacte'd with molecular proportions of 98% hydrogen'fluorlde at -25 C. A mixture comprising essentially the isopropyl fluoride so formed and the excess ,of hydrogen fluoride is separated asaa solution from a substantially propane fraction which is discharged from the process. The

solution of isopropyl' fluoride in hydrogen fluoride so obtained is then introduced to a second mixing zone together with 3 molecular proportions of benzene and the reaction-mixturewlthin said second zone is maintained at 50 C. and

andcatalyst. The resultant lnixture-is separated into a hydrocarbon layer and a hydrogen fluoride layer, the latter being recycled in part to the first stage of the process in which isopropyl A 5 fluoride is formed. The hydrocarbon layer is fractionally distilled to separate excess be; 'ene from the alkylated benzenes, the excess benzene being recycled to the alkylation stage while the alkylated benzenes are .fractionally distilled and thereby separated into isopropyl benzene, diisopropyl benzene, and more-highly alkylated hydrocarbons. The total allrylated product comprises about 80% by weight of mono-isopropyl benzene and 20% by' weight of poiy isopropyl benzenes. v

with liquid hydrogen fluoride while ethane is' flcient to maintain in'substantially liquid state resentative of results obtainable by the process stirred to of act intimate contact of the reactants aromatic hydroc r on and used hydrogen fluoride from said reaction mixture, recycling said uncon norinal parafllns.

2. A process for i'eiis ii. a c r -mimi s ai clave'providedwith a motor-drivenstirrer, The

autoclave and contenta-areqthen brought to a temperature of 0 C. and 0 ,grams of a solution, consisting of equal parts by weight oi ethyl fluoride and.hydrogen fluoride resulting from treatment or an ethane-ethylene fraction with liquid hydrogen fluoride at 50 -C is slowly. introducedto the autoclave with stirring during a period of l, hour and then the stirring iscontinued for another hour at the operating, teman excess or liqiudhydrogen fluoride at afteni under aliqueiying pressure with oleflns present.

in ahydrocarbon'fraction containing both oleflns perature of from about -50 to a'bout'f+50 C.

and normal paraflins, separating as a relatively heavy layer a solution of the resultant alkyl fluorides in the excess hydrogen fluoride-from a relatively lighter layer comprising essentially un- I converted normal parafllns, subjecting said solution. to contact with an aromatic hydrocarbon under alkylating conditions to form a-Ireaction perature' of 50 CL mm: the autoclave is cooled I to room temperature, thereactlon products are removed and separated into 84 grams of unconverted ethyl fluoride and 200 grams of a waterinsoluble 011. After distillation to remove unconverted .benzene'there/remains 12 grams 'oi 'mono=e thy1 benzene and 4' of more' hig'hly alkylated benzene. -In,a similar'run but at 100 C. reaction temperatu the yield of mono-ethyl benzene is about 100 grams. c

mixture containing ,alkfylated aromatic hydrocarbons, separating-from said reaction mixture unconverted; aromatic hydrocarbons, alkylated :aromatic hydrocarbons, and used hydrogen fluoride, recycling said unconverted aromatic hydro- 4 carbons tofurther reaction with said solution of alkylfluorides in hydrogen fluoride, and returning. atleast a portion of said used hydrogen fluoride to contact with the charged fraction c'ontaining both oleflns and normal paraflins.

The: character of the process or'tliepresent invention and particularly its commercial value are evident fromthe preceding specification ,and

examples; although neither section 'is intended to be unduly limiting in its generally broad scope.

I claim as my invention: a l. Aprocess for the manufacture of alkylated aromatic hydrocarbons which comprises reactmg an excess of liquid hydrogen fluoride with oleflns present in a hydrocarbon fraction containing both oleflns and normal paraflins, separating as a'nrelatively heavy layer a solution of F the-resultant alkyl fluorides in the excess hydro.- 'gen'fluoride from a relatively lighter layer com- I prising'essentiallyfunconverted normal 'paraflln's,

subjecting'said solution to contact with an'aromatic hydrocarbon under alkylating conditions to form a reaction mixture containing alkylated aromatic hydrocarbons, separatingunconverted hydrocarbons, alkylated aromatic verted aromatic hydrocarbons to further reaction with said solution oi alkyl fluorides in hydrogen fluoride,- and returning at least a portion of l said u se'd hydrogen fluoride to Contact 'with the charged traction containing botlr olefins and the manufacture of alkylated aromatic hydrocarbons-which comprises reacting an excess of liquid hydrogen fluoride at a temperature of from about to about +50' C. with oleflns presenthn ahydroca'rbon' fraction 1 containing both oleflns and normal parafllns, separating as a relatively heavy layera solutionor the resultant allryl fluorides in the excess hydrogen fluoride from a relatively lighter layer comprising essentially unconverted normal par amns, subjecting said solution to contactwith' an aromatic hydrocarbon under alkylating conditions to form a reaction mixture containing alkylated aromatic hydrocarbons, separating from said reaction mixture unconverted aromatic hydrocarbonsialkylated aromatic hydrocarbons, and used hydrogen fluoride, recyclingsaid unconverted-aromatic hydrocarbons to flirther-reaction with said solution of alkyl-fluorides in hydrogenfluoride, and returning atleast a por tion of said used hydrogen fluoride to contact with the charged traction containing botholeflns and normal parafllns 3. A process for the manufacture of alkylated aromatic hydrocarbons which comprises reacting v 4. A process'for the manufacture of alkylated aromatic hydrocarbons which comprises reacting anexcess of liguid hydrogen fluoride at a temperature of from'. about -50 to about +50 C. under a liquefying pressure with oleflns present in a/ hydrocarbon fraction containing both oleflns and normal paraflins, separating as a relatively heavy ,layer a solution of the resultant alkyl fluorides in the excess hydrogen fluoride from a relatively lighter layer. comprising essentially unconverted normal paramns, subjecting said solution tocontact with anaromatic hydrocarbon at a temperature between about l0 and about 150 C; toform areaction mixture containing alkylated aromatic hydrocarbons, separating from "said reaction mixture unconverted aromatic hydrocarbons, alkylated aromatic hydrocarbons, and used hy ogen fluoride, recycling said unconverted aro atic hydrocarbons to further reaction with said solution of alkyl fluoride'sin hydrogen fluoride, and returning. at least a portion of said -used hydrogen fluoride to .contact with the hydrocarbon fraction containing both oleflns and normal parafllns, separating as a relatively heavy layer a solution of the resultant alkylfluorldes in the excess hydrogen; fluoride froini a-relatively lighter layer composed of unconverted normal 'p'araflins, subjecting said solution to contact with I an aromatig hydrocarbon ata temperature between abo containing alkylated aromatic hydrocarbons,

I separating from said reactionmixture unconverted aromatic hydrocarbons, alkylated aromatic hydrocarbons, and used hydrogen fluoride,

recycling saidunconverted aromatic hydrocarbons; to further reaction withsaid solution of' alkyl fluorides in hydrogen fluoride, and returning,at least a portion of said usedhvdrogen fluoride. to contact with the charged fraction containingbothioleflns and normal Paramns.

A process tor the manufacture of ethyl benzene which comprises reacting an ethane-ethylene fraction with a substantial molar" excess of hydrogen fluoride relative to said ethylene, sepa- -10 and about, C. under apressure siifllcient to maintain in liquid state a. substantial proportion .of the reactants and hydrogen fluoride to form a reaction mixture,

2 rating as a relatively heavy layer a solution of tion to contact with benzen the resultant ethyl fluoride in the excess hydrogen fluoride from a relatively lighter layer composed essentially of ethane, su Jecting said soluunder alkylating conditions to form a reaction mixture containing ethyl benzene, separating from 'said reaction mixture unconverted benzene, ethyl benzene, and

. used hydrogen fluoride, recycling said benzene to further reaction with said solution of ethyl fluoride in hydrogen fluoride, and returning at least a portion of said used hydrogen fluoride to contact with the charged ethane-ethylene fraction.

7. A process for the manufacture of ethyl benzene which comprises reacting an ethane-ethylene fraction with a substantial molar excess of hydrogen fluoride relative to said ethylene at a temperature of from about 50 to about -+50 separating as a relatively-heavy layer a solution of the resultant ethyl fluoride in the excess hydrogen fluoride from a relatively lighter layer composed essentially of ethane, subjecting said relatively heavy layer a solution of the resultant ethyl fluoride in the excess hydrogen fluoride olution to contact with benzene under alkylat- 'ing conditions to form a reaction mixture contemperature of from about 50 to about -F50" C. under a liqueiying pressure, separating as a 1 relatively heavy layer a solution of the resultant ethyl fluoride in the excess hydrogen fluoride from a. relatively lighter layer composed essentially of ethane, subjecting said solution to contact with benzene under alkylating conditions to form a reaction mixture containing ethyl benzene, separating from said reaction mixture unconverted benzene, ethyl benzene, and used hydrogen fluoride, recycling said benzene to further reaction with said solution of ethyl fluoride .in

hydrogen fluoride, and returning at least a por tion of said used hydrogen fluoride tocontact with the charged ethane-ethylene fraction.

9. A process for the manufacture of ethyl benzene which comprises reacting an ethane-ethylene fraction with a substantial molar excess of hydrogen fluoride relative to said ethylene at a temperature of iromabout -50 to about +5 0 from a relatively lighter layer composed essentially of ethane, subjecting said solution to contact with benzene at a temperature between about -l0 and about 150 C. under a pressure sufficient to maintain in liquidstate a substantial proportion of the reactants and hydrogen fluoride to form a reaction mixture containing ethyl benzene, separating from said reaction mixture unconverted benzene, ethyl benzene, and used hydrogen fluoride, recycling said benzene to further reaction with said solution of ethyl fluoride in hydrogen fluoride, and returning at least a portion of said used hydrogen fluoride to contact with the charged ethane-ethylene fraction.

,10. ,A process for the manufacture of propylated benzene which comprises reacting a propanepropene fraction with a substantial molar excess of hydrogen fluoride relative to said propene at a temperature of from about to about +50 C. under a 'liquefyingpressure, separatingas a relatively heavy layer a solution of the resultant I isopropyl fluoride in the excess hydrogen fluoride from a relatively lighter layer' composed essentially of propene, subjecting said solution to contact with benzene at a temperature of between about l0 and about 15070. under a pressure suflicient to maintain in liquid state a substantial proportion of the reactants and hydrogen fluoride to form a reaction mixture containing isopropyl benzene, separating from said reaction mixture unconverted benzene, isopropyl benzene, and usedhydrogen fluoride, recycling said benzene to further reaction with said solution of isopropyl fluoride in hydrogen fluoride, and returning at least a portion oi said used hydrogen fluoride to contact with thecharge d propane-propene fraction.

6 11. A process for producing alkylated aromatics which comprises subjecting a mixture of oleflns and paraflins to reaction with liquid hydrogen fluoride to react oleflns with hydrogen fluoride and thereby form alkyl fluorides,said reaction being effected in the presence of an amount 0! hydrogen fluoride which is in excess of that required to react, with the oleflns, thereby forming a solution of the alkyl fluorides in the excess of hydrogen fluoride, separating said solution from unreacted paraflins and commingling an aromatic hydrocarbon therewith, and subjecting the resultant mixture' to alkylating conditions to alkylate V the aromatic hydrocarbon;

' I CARL B. LINN.

C. under a liquetylng pressure, separating as a' 

